if you have a self-moderated topic, you can move it to Meta board and it will lost the self-moderated option.
You shouldn't (ab)use Meta for this:
Archival is the place to be to get rid of self-mod status.
Thanks for the advice LoyceV.
I did not mean to abuse Meta board for this purpose. It is my example because I only know Meta board does not allow self-moderated topics. The announcement thread for self-moderated option from theymos revealed that there are a few sections (boards) in which self-moderated option is not allowed. I don't know others beyond Meta.
More important, I think the most common situation is when people want to convert non-self-moderated topic to self-moderated.